Photosensitive opal glass



July 18, 1950 vs. D. STOOKEY 2,515,940

'PHOTOSENSITIVE QPAL GLASS Filed Sept 9, 1946 IN V EN TOR.

JrA/nsy fialmw Jroom r BY i7) above '-mentioned patent applications.

Patented July 18, 1950 "PHOTOSENSITIV E =PAL :GLASS Stanley Donald'Stookey, Corning, N. Y., assignor toCorning Glass -WorksgG0rning, N.Y., a corporation of New York Application September 9, 1946, SerialNo.695,801

21 Claims. (01. '4992) 513,441, 513,443, and 513,444 filed December 8,

1943, there are described colorlessphotosensitive glasses 'in which acolored photographic image may be formed by exposure throughla suitable"negative followed by heating the glass. -Inthe glasses sotreated thecontrast-betwen high lights and low lights is a variation in the density'of "the color of the light-aifected areas of the glass.

"In my pending application, Serial Number "513,445, filed December '8,1943, I have "described colorlessphotosensitive glasses in which acolored "photographicimage likewise may be formed and "devloped bysuitableexposure through 'a negative and subsequent heatingbutwhi'chbecome opacified throughout during heating'to provide a 'whiteopaquebackground for the colored image.

The primary object of this invention is to :pro-

"videphotosens'itive"glasses in which only the de- "velopedimage isopaque or glasses in which light- "aiifectedareas becomeopacified onheating While unexposedareas with the same heat treatment -remain clearand unchanged.

Another object is to providecolorl'ess photosensitivefglas'sesin whichthe developed image is bothopaquean'd colored "while unexposed areasremain {clear and unchanged during heating.

'1 have discoverednewphotosensitive glass com- 'positionsin whichselective irradiation and subsequent heating produce in the glass anopaque image by'the differential precipitation of 1 either'lithiizmdisilioat'e or barium disilicate in the irradiated areas duringheating. To cause such selective precipitation-of the opacifyingdisilicate particles it is necessary to incorporate into the glass -one*of the photosensitizing metals, gold, silver or 'copper employed in theglasses of the These makethe glass sensitive to short wave radiationsand-on subsequentheatingof the glass they :provide colloidal nucleiforthe formation and growth of theopacifying crystallites. -In anotherapplication Serial Number 695,802, filed by the con-"' currentIyhereWith, 'I have described and claimed photosensitive glasses andarticles inwhich the "image formingcrystallites are barium disilicate.-The present application is specifically directed to glasses andarticles in which photographic images are .formed by the differentialprecipita- -tion of' 1ithium disilicate.

The glasses of the present invention are silicate "gla'ssescontaining to25% L120 and a in or copper as a sensitizing metal.

goldsilver or copper. These glasses preferably but not esseritiallycontain up to 5% of BaQ or 'up"to1'0%*of another oxide of the secondperiodic group or up to 10% A1203 or up to 10% of am 5 other alkalimetal oxide or combinations thereof.

Compositions containing both L120 and BaO preferably comprise 55% to 75%SiOz, 10% to 25% LizO and 3% to 35% BaO to which is added asmall amountof a salt or oxide of gold, silver In glasses of the :above mentionedcompositions containing both H and BaO, some barium disilicate mayalsotbe precipitated but lithium disilicate is always :formed as thechief opacifying agent.

llfhe new glasses are transparent and uncolored by .jth'e sensitizingmetal when fabricated, but when exposed to short wave radiations andsubsequently heated the exposed areas become opacified by-t-heprecipitation of lithium disilicate while -20 the unexposedareas remainclear. The minimum amounts of the sensitizing metals which are effectiveto :induce 'opacification of the exposed areas "are iequivalent on theoxide basis to 004% 'of i-gold compu'ted as -Au, .025% of silvercomputed as Ag'Cl and 104% of copper computed as CuzO respectively. Theopacification of the exposed areas is progressively intensified byincreasing the 'amounts o'f the sensitizing metals up to maximum amountswhich are'equivalent on the oxide basis to about 05% *of goldcomputed-as Au, .3% of silver computed as AgCl and 1%ofcopp'er com-'puted as "CuO. Maximum opacification is also produced by 'still largeramounts, but their use i's impractical for economic reasons. The'expOsedand -Opacified areas maybe colored by the isensitizin'g metals ifsufficient amounts within the above recited ranges are used and if theirradia- "tion and subsequent heat treatment of the glass *aresufiiciently intense or prolonged, as will later 40 appear. "The colorsobtained through the u'se'of :golcl may :varyfromblue through'lavenderand pinkto red; silver produces a yellow or brown "coloration, and a'redor reddish brown may be obtained with copper. Under conditions which1645 produce .i'color-ati-on, the opacification of the iri'radiatedareas-of the glass occurs subsequent to "their coloration. i I

:In general, the=use of the sensitizing metals gold;:"silver*andcoppen'in the new glasses is sub- -ject to the-sameconsiderations andlimitations which attend their use'in 'the glasses disclosed inithepending applications above referred to. Rel ducing agents preventphotosensitivity in gold and silver containing glasses but notin copperissrcontaining glasses. 'In all cases, photosensitivity ispreventedi'or"-objectionably diminished by the :presence of substantialamounts of compounds of arsenic, lead, -thalli-um; vanadium, uranium;iron, manganese or-selenium. As the sensitizing metal,

small amount iofoneiof the photosensitive metals; figold is preferableand is introduced into the batch prevented by using an amount of themetal too .in a given glass than for the development of the as asolution of gold in acid to form gold chloride.

Cerium in small amounts intensifies the photosensitivity of glassescontaining either gold or Fig. 2 is a sectional view on an enlargedscale silver or copper, that is, it increases the effect 'on line 2-2 ofFig. 1 showing that the opacifying of a given exposure or shortens thetime of excrystallites forming the design are present posure necessaryto produce a given effect. In throughout the thickness of the glass sothat the large amounts, it decreases or prevents the photodesign isthree-dimensional and extends comsensitivity of the glass. The maximumintensifypletely through the glass panel. ing effect of cerium occurs inglasses containing Fig. 3 is an enlarged sectional view of a glass about.04% CeOZ and not more than .05 %..CeOz ll. panel similar to that shownin Fig. 2 and containshould be employed. ing a design comprising blockletters as in Fig. 2 In glasses containing gold, the addition of upwhich are opaque white in the section designated to .03% $1102 or 813203tends to prevent a blue M at the back of the panel, and are atransparent and to permit only a red coloration to develop in red colorin the section designated l 5 at the front the surface of the irradiatedarea of the glass of the panel. during heating. The development ofopacity in The following batches in parts by weight are the same areasubsequently occurs only below given as examples to illustrate but notto limit the surface where the glass has not become red. my invention:

block letters ll, l2 and I3, the glass being otherwise clear andcolorless.

This results in a transparent red image super- When the above batchesare melted in the imposed on a white opaque image. The density usualmanner and fabricated they produce subof the coloration in the presenceof SnOz or stantially transparent glasses which, when ex- $13203increases with increasing gold content and posed to short Waveradiations and subsequently the depth to which the coloration extends orpenereheated, will become opacified in the exposed trates into the glassincreases with increasing areas but will remain unchanged in theunexposed time of exposure of the glass to short wave radiareas. ations,The proper time of exposure and subsequent Coloration of the irradiatedareas of the glass h treatment of e neW glasses Will depend by thesensitizing metal during heating may be upon the content of sensitizingmetal, the character and intensity of the light source and the colorsmall to produce coloration, though sufficient to efiects desired. Ingener When plates of las produce opaoification, or by employing largermade from the above compositions are exposed amounts of the metal andusing an exposure time from 1 to 10 minutes, either directly or th orintensity sufficient to bring about opaoification a S b pho e ap e t veat a distance of but insuflicient to permit a visible coloration to ll-inches from a 60 ampere carbon are usin develop on heating. Suchexposure conditions carbon electrodes (manufactured by The Navary withdifferent compositions but may readily tionel rbon Company) and aresubseque be determined by trial, The temperature for the h ed f r 10minutes o an hour or more at 540 development of opaoification issomewhat higher to an pa fi at w be d p d n th irradiated area of theglass while the unexposed color of the sensitizing metal and is about100- .,,55 portion Will remain eleerf the e posure is c. or less belowthe softening point of the glass. made through a ph ap i n ativ th pColoration without opaoification may therefore .fi i n will form a p s vimage in minute debe produced by'using temperatures high enough tail inthe glass. More specifically for example, to cause coloration of theexposed areas but not composition 1 w d v l p a p k pal with a 10 highenough to zause opaoification thereof. minute exposure followed yheating for a w From the foregoing description it will be seen minutesat C- C si i 6 wi l develop a that various effects can be produced bymeans yellow p under the some conditionsp of the invention. Such effectsinclude white Si 7 Will develop a White p When posed opacified images ordesigns co1ored pacified for 5 minutes and heated at 600 C. Byincreasmaees or designs, and a colored but unopacified mg the time ofexposure o p s on '7 or by image or design in the surface of the glasssuperincreasing its content of reducing agent, 4 imposed on an id tipacified image or design ,the opacified area will acquire a reddishcolor. within t body of t glass, any one n of The effect of theirradiation and the image prowhich can be produced in a single glassarticle. dnced by heating the irradiated glass e tend from Theaccompanyin drawin ill t t articles 7 the surface into the glass usuallyto a depth of 1 made in accordance with the invention. to 5 more,depending upon the time Fig. 1 is a plan view of a glass a l In i hi andintensity of exposure and the content of senl ght-diffusing oropacifying microscopic crystal- SitiZing metal d being greater as the poure lites of lithium disilicate are precipitated in the v or thesensitizing metal content is increased. glass to form a white opaquedesign comprising X-ray diffraction patterns of the new glasses afterirradiation: andaheat ctreatment' :show that ystalsaof ilit'hillmxdisilicate are '1 present in the .opacifiedxareas but are notpresent inthe clear or unopacified areas. Such crystals are microscopicxin sizeand areiprecipitatediduring the heat treatment.

, .1 Ultravioletiemitting lamps, such asthe carbon arc'saortherquartarmercury are, are convenient sources'nfrradiations which areeffective for my purpose; buttreatment's with X-rays, radioactiveradiations and other sources of radiations shorter 'than400"millimicrons are included"within the scope of the present invention.

Thevnew "glasses are'useful for many purposes such as: "illuminatingware of various kinds, signalling :devices, I headlights, windows, etc.,in whiohlitransverse; opaque or opalescent' ribbons within the otherwiseclear glass are employed as louvrcsto' transmit direct light in somedirections buti to cut "off or transmit only diffused light in others; 1illuminated decorative photographs, block letter signs; etc., whereinthree-dimensional:light scattering images are employed to produce unique'e'ffects with oblique illumination; photographicpp'al :designs in glasstableware; durable, permanent images for projection, .as in lanternslides. 'In m'aking such articles, the desired designs, transverselouvres', images, etc., are produced in the glassby irradiation thereofthrough appropriate photographic negatives followed byuniformly'heating' the glass throughout, as set forth above.

The term fsilicateglassfasused in the claims, meansi'a glass prepared'by fusionof raw glassmaking 1 materials containing, on the 1 oxidebasis, a maj'or proportion of silica, a minor proportion (if lithiumoxide preferably containing up to of another alkali metaloxidesuchassodium oxide, or=up to of BaO, orup tol=0% of an oxideofwanother metal'ofthe second'periodic group, or up to' 10% of-alu'mina,but being free of constituents'whi'ch inhibit photosensitivity includingcompounds "of arsenic, lead; thallium,

vanadium, uranium, "iron; selenium.

*' I'claim:

1. A photosensitive glassconsisting essentially of a silicate glasscontaining, on the oxide basis by'weigh't, 10% 'to 25% LizO and theindicated proportion "of a photosensitive metal selected fromthegroup'consisting of 0.004% to0.05% of gold computed'as Au',' 0.025%to0.3% of silver computed as AgCl and 0.04% to 1% of copper computed asC1120.

l 2; A'photosensitiveglass consisting essentially of a-"silicate' glasscontaining, on the'oxide basis by weight, 10% to 25%Li20 and theindicated proportion of *a photosensitive metal selected fromthegroup'consisting of"0 '.004% to 0.05% of gold computed as Au, 0.025%to 0.3% of silver computed as AgCl and 0.04% to 1% of copper computedas-"Cuz0; andCeoz in an'amount up to 0.05%.

3. A photosensitive glass consisting essentially of tasilicatewglasscontaining, on the oxide basis by weight, 10% to 25% LiZO and-theindicated proportion ofp'a photosensitive metal selected from the groupconsisting of 0.004% to 0.05% of gold computed as Au, 0.025% to 0.3% ofsilver computed at AgCtl and 0.04%"to 1% of copper computed-at Cuzo andS1102 in an amount up too.03%.

4: A photosensitive glass consisting essentially ofa silicate glasscontaining'on the oxide basis by weight, 10% to 25% L120 and theindicated manganese and proportion of a photosensitive .metal"; selectedfrom the group consisting.of0004% to 0.05% of gold:comp.uted as Au,0.025%.t0 0.3% of silver computed as AgCl and 0.04% to 1% of coppercomputedas C1120; and SbaOsin an amount up to 0.03%. 1

5. A photosensitive glass consisting essentially of a silicate-glasscontaining, on theoxide-basis by Weight, 10% to 25% L120 and theindicated proportion 'of a photosensitive metal'selected from the groupconsisting. of 0.004% to=0.05'%' of gold-computed as Au; 0.025% to0.3%ofsilver computed as AgCl and 0.04%.to 1% .ofcopper computed asCuzO, C602 in an i amount up to 0.05% and SnOz in an amount up to 0.03%.I

6. A photosensitiveglass consisting essentially of an oxidized silicateglasscontaining, on the oxide basis by weight; 55% to75%*SiO2',"10% to25% LizO, 3% to 35% BaO, 0.004% to 0.05% of gold computed as Au, andCeOeinan' amount up to 0.05%.

- '7. A-photosensitive glass consisting essentially of an oxidizedsilicate glass containing, on the oxide basis -byweight, 55% to '75S102, 10% to 25% LizO, 3% to'35%' BaO, 0.025% to 0.3% of silver computedas AgCl, and C602 in an amount up to 0.05%. i

8; A photosensitive, glass consisting essentially of a reduced silicateglass containing, on the oxide basis by-Weight, 55% to S102, 10% to 25%LizO', 3% to 35% BaO, 0.04% to 1% of copper computed as CuzO, andCeOz inanamount up to'0.05%.

9. 'An article comprising abody of irradiated substantially colorlessphotosensitive glass consisting essentially of "a'silicateglasscontaining, on theoxide basis by weight, 10% to 25% Li'zO and theindicated proportion of a photosensitive metal selected from the groupconsisting'of 0.004% to"0.05% of-goldcomputed as An, 0.025% to 0.3% of'silver'computed as AgCl and 0.04% to 1% of copper computed asCuzO,'said' glass body containing within its mass a predeterminedlatentimage capable of being developed, by'uniform heating of the entire glassbody, into a visible opacified image exhibiting photographic. detail andcomprising light-diffusing crystallites of lithium disilicate.

10. Anarticle comprising a body of irradiated substantially colorlessphotosensitive glass consisting essentially of .a silicate glasscontaining, on the oxide basis by Weight, 10% to 25% ,LizO, theindicatedproportion of a photosensitive metal selected from the groupconsisting of 0.004% to 0.05% of gold computed as Au,'0.025% to 0.3% ofsilver computed as AgCl and. 0.04% to 11%, of copper computed as 01120,andCeO in an amount up to 0.05%, said glass, body containing withinitsmass a predeterminedv latent image capable of being developed, byuniform-heating'of the entire glass, body, into a visible opacified.image ex,- hibiting photographic detail and comprising lightdiflusingcrystallites of lithium disilicate.

1.1. An article comprising a, body of irradiated substantially colorlessphotosensitive glass consisting essentially of a silicate glasscontaining, on the oxide basis by weight, 55% to,75%,SiO2, 10%to25%.Li20, 3% to 35% BaO,,the indicated proportion of a photosensitivemetal selected from the group consisting. of-0.004 to 0.05% of. goldcomputed as An, 0.025% to 0.3 of silver computed as AgC1 and-0.04% to 1%of copper ,co nputedas GuzO, and (15202 in an. amount up.to.0.05.%,.said glass body containin within its mass a predeterminedlatent photographic image capable of being developed, by uniform heatingof the entire glass body, into a visible opacified image exhibitingphotographic detail and comprising light-diffusing crystallites oflithium disilicate.

12. An article comprising a body made of a photosensitive glassconsisting essentially of a silicateglass containing, on the oxide basisby weight, to L120 and the indicated proportion of a photosensitivemetal selected from the group consisting of 0.004% to 0.05% of goldcomputed as Au, 0.025% to 0.3 of silver computed as AgCland 0.04% to 1%of copper computed as CuzO, selected portions of said glass bodycontaining light-diffusing crystallites of lithium disilicate inquantity and arrangement to form within its mass a heat-stable opaqueimage exhibiting. photographic detail.

' 13. An article comprising a body made of a photosensitive glassconsistin essentiall of a silicate glass containing, on the oxide basisby weight, 10% to 25% LizO, the indicated proportion ofa photosensitivemetal selected from the group consisting of 0.004% to 0.05% of goldcomputed as Au, 0.025% to 0.3% of silver computed as AgCl and 0.04% to1% of copper computed as CuzO, and CeOz in an amount up to 0.05%,selected portions of said glass body containing lightdifiusingcrystallites of lithium disilicate in quantity and arrangement to formwithin its mass a heat-stable opaque image exhibiting photographicdetail.

14. An article comprising a body made of a photosensitive glassconsisting essentially of an oxidized silicate glass containing, on theoxide basis by weight, 55% to 75% SiOz, 10% to 25% U20, 3% to BaO,0.004% to 0.05% of gold computed as Au, and CeOz in an amount up to0.05%, selected portions of said glass body containing light-diffusingcrystallites of lithium disilicate in quantity and arrangement to formwithin its mass a heat-stable opaque image exhibiting photographicdetail.

15. An article comprising a body made of a photosensitive glassconsistin essentially of an oxidized silicate glass containing, on theoxide basis by weight, to S102, 10% to 25% 1.120.3 5 to 35% BaO, 0.025%to 0.3% of silver computed as AgCl, and CeOz in an amount up to 0.05%,selected portions of said glass bod containing light-difiusingcrystallites of lithium disilicate in quantity and arrangement to formwithin its mass a heat-stable opaque image exhibiting photographicdetail.

16. An article comprising a body made of a photosensitive glassconsisting essentially of a reduced silicate glass containing, on theoxide basis by weight, 55% to 75% SiOz, 10% to 25% L120, 3% to 35% BaO,0.04% to 1% of copper computed as CuzO, and CeOz in an amount up to0.05%, selected portions of said glass body containing light-difiusingcrystallites of lithium disilicate in quantity and arrangement to formwithin its mass a heat-stable opaque image exhibiting photographicdetail.

17. An article comprising a body made of a photosensitive glassconsisting essentially of a silicate glass containing, on the oxidebasis by weight, 10% to 25% L120, the indicated proportion of aphotosensitive metal selected from the group consisting of 0.004% to0.05% of gold computed as Au, 0.025% to 0.3% of silver computed as AgCland 0.04% to 1% of copper computed as C1120, and SnOz in an amount up to0.03%, selected portions of said glass body containing light- 8diffusing crystallites of lithium disilicate in quantit and arrangementto form within its mass a heat-stable opaqueimage exhibitingphotographic detail.

18. An article comprising a body made of a photosensitive glassconsisting essentially of a silicate glass containing,'on the oxidebasis by weight, 10% to 25% L120, the indicated proportion of aphotosensitive metal selected from the group consisting of 0.004% to0.05% of gold computed as Au, 0.025% to 0.3% of silver computed as AgCland 0.04% to 1% of copper computed as CuzO, and SbzOa in an amount up to0.03%, selected portions of said glass body containing lightdiffusingcrystallites of lithium disilicate in quantity and arrangement to formwithinits mass a heat-stable opaque image exhibiting photographicdetail. I

19. An article comprising a;,body made of a photosensitive glassconsisting essentially of :a silicate glass containing, on the oxidebasis by weight, 10% to 25% L120, the indicated propor-' tion of aphotosensitive metal selected, from-the group consisting of 0.004% to0.05% ofgold computed as Au, 0.025% to 0.3% iof-silver computed as AgCland'0.04% to 1% of copper computed as C1120, C602 in an amount up to0.05% and-SnOz in an amount up to 0.03%, selected portions of said glassbody containing light-diffusing crystal-.- lites of lithium disilicatein quantity and arrangement to form within its mass a heat-stable opaqueimage exhibiting photographicdetail.

20. An article comprising a body made of a photosensitive glassconsisting essentiall .of a silicate glass containing, on the oxidebasis by weight, 10% to 25% L and the indicated proportion of aphotosensitive-metalselectedfrom the group consisting of 0.004%: to0.05% of gold computedas Au, 0.025% to 0.3% of silver computed as AgCland 0.04% to 1% of copper computed as CuzO, selected portionsof saidglassbody containing light-diffusing crystallites of lithium disilicatein quantity and arrangement to form within its mass a heat-stable opaqueimage exhibiting photographic detail, and superimposed on said opaqueimage and in register therewith a colored unopacified image. i

2 The method of making a glass article which comprises forming anarticle of a photosensitive glass consisting essentially of a silicateglass containing, on the oxide basis by weight, 10% to 25% L120 and theindicated'proportion of a photosensitive metal selected from the groupconsisting of 0.004% to 0.05% of gold computed as Au,0.025% to 0.3% ofsilver computed as AgCl, and'0.04% to 1% of copper computed as C1120,exposing an area of the article to short-wave radiations and thereafterheating the article uniformly for a time and at a temperature sufficientto cause precipitation of lithium disilicate crystallites in the exposedarea. I

STANLEY DONALD STOOKEY.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,049,765 Fischer Aug. 4, 19362,144,943 Sharp et al Jan. 24, 1939 2,237,042 Truby Apr. 1, 19412,326,012 Dalton Aug. 3, 1943 2,422,472 Dalton June1-7, 1947 Certificateof Correction Patent No. 2,515,940 July 18, 1950 STANLEY DONALD STOOKEYIt is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows:

Column 2, line 32, for CuO read OM20;

and that the said Letters Patent should be read as corrected above, sothat the same may conform to the record of the case in the PatentOflice.

Signed and sealed this 7th day of November, A. D. 1950.

THOMAS F. MURPHY,

Assistant Commissioner of Patents.

9. AN ARTICLE COMPRISING A BODY OF IRRADIATED SUBSTANTIALLY COLORLESSPHOTOSENSITIVE GLASS CONSISTING ESSENTIALLY OF A SILICATE GLASSCONTAINING, ON THE OXIDE BASIS BY WEIGHT, 10% TO 25% LI2O AND THEINDICATED PROPORTION OF A PHOTOSENSITIVE METAL SELECTED FROM THE GROUPCONSISTING OF 0.004% TO 0.05% OF GOLD COMPUTED AS AU, 0.025% TO 0.3% OFSILVER COMPUTED AS AGC1 AND 0.04% TO 1% OF COPPER COMPUTED AS CU2O, SAIDGLASS BODY CONTAINING WITHIN ITS MASS A PREDETERMINED LATENT IMAGECAPABLE OF BEING DEVELOPED, BY UNIFORM HEATING OF THE ENTIRE GLASS BODY,INTO A VISIBLE OPACIFIED IMAGE EXHIBITING PHOTOGRAPHIC DETAIL ANDCOPRISING LIGHT-DIFFUSING CRYSTALLITES OF LITHIUM DISILICATE.